Allegro MicroSystems Inc.'s complete three phase brushless DC
motor pre-driver has outputs for direct high current gate drive of an all
N-channel power MOSFET. The three phase bridge has a maximum supply voltage of
38 V. The A4938 includes Hall element inputs, a sequencer
for commutation control, fixed off time pulse width modulation (PWM) current
control and locked rotor protection. Output current is scalable with the choice
of external MOSFETS. ENABLE, DIRECTION and BRAKE inputs can be used to control
the motor, speed, position and torque. Output speed can be regulated using open
drain FG1 output that changes state at each Hall transition.
external MOSFETS can be PWM'd with the ENABLE input or with the internal PWM
current regulator. In both cases the A4938 synchronous rectification feature
will turn on the appropriate MOSFET(s) during current decay to reduce power
dissipation. The A4938 uses low cost Hall elements with noise filtering to
prevent false commutation signals. A 5V regulated supply output is provided to
power the three HALL elements. Internal circuit protection includes thermal
shutdown with hysteresis, under voltage lockout, over voltage protection with
two voltage settings, locked rotor and dead time protection. Special power up
sequencing is not required. Operating temperature range is -40 to 85C. The A4938EETTR-T is supplied in a 5 ×
5 mm 28-lead QFN package with exposed thermal pad.
A flyer or flier, also called a circular, handbill or leaflet, is a form of paper advertisement intended for wide distribution and typically posted or distributed in a public place or through the mail.
Lithium-ion battery prices will drop rapidly over the next 10 years, setting the stage for plug-in vehicles to reach 5%-10% of total automotive sales by the mid- to late-2020s, according to a new study.
Two researchers from Cornell University have won a $100,000 grant from NASA to continue work to develop an energy-harvesting robotic eel the space agency aims to use to explore oceans on one of the moons of Jupiter.
Is the factory smarter than it used to be? From recent buzzwords, you’d think we’ve entered a new dimension in industrial plants, where robots run all physical functions wirelessly and humans do little more than program ever more capable robotics. Some of that is actually true, but it’s been true for a while.
A recent Design News-exclusive study proves that engineering professionals are at the very forefront of this push into the future and making direct financial, performance, and value impact on their organizations by being personally involved or final decision-makers on automation solution and component choices.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.